The goal of this Mentored Patient-Oriented Research Career Development Award (K23) is to develop the applicant into an independent investigator prepared to lead large-scale rigorously designed treatment outcome research focused on high-risk youth. Specifically, the applicant will focus on integrated treatments for substance use disorders (SUDs) and posttraumatic stress disorder (PTSD) targeting high-risk transition age youth. The proposed career development and research plan builds on the applicant's prior training in clinical psychology, trauma populations, and PTSD treatments. The research aims are consistent with Goal 2 of the NIDA Strategic Plan, to develop successful treatments for drug abuse and addiction and improve treatment accessibility and implementation and specifically, Objective 2.2, to develop treatments for drug abuse and addiction in association with comorbid conditions. Through the proposed training plan, the applicant will: (1) develop expertise in evidence-based SUD treatments; (2) develop the skill set to conduct clinical trials; (3) become proficient in approaches for integrating interventions for SUDs and PTSD; and (4) gain expertise in the study and treatment of transition age youth. Training activities will include mentorship from a team of experts in the fields of SUDs treatments, clinical trials, and transition age youth; intensive training in SUDs treatment; [expert consultation and training on longitudinal statistical methods;] coursework and lectures on conducting clinical trials and protection of human subjects; and participation in scientific workshops and conferences. The applicant will apply these skills to pilot research aimed at developing and evaluating an integrated SUD/PTSD treatment for high-risk transition age youth through the integration and adaptation of existing empirically supported interventions for SUDs (Contingency Management) and PTSD (Prolonged Exposure). The project will be conducted in [three phases]: 1) integration and adaptation of the treatment protocol using an iterative approach; [2) initial piloting and revision of the protocol b the applicant;] and 3) a pilot feasibility study of the integrated treatment with a sample of [30] justice-involved transition age youth to examine acceptability, safety, and symptom reduction in both primary (self-report and biological measures of substance use, self-report and interview measures of PTSD) and secondary outcomes (self-report and archival records of criminal justice involvement, self-report of adaptive functioning). The proposed research plan will adhere to the treatment development recommendations of the Stage Model of Behavioral Therapies (Carroll & Nuro, 2002), with a focus on Stage 1a and 1b research. Given the high rates and particularly detrimental effects of comorbid SUD/PTSD among transition age youth, the goals of this application have the potential to address an important and costly public health problem. As the presence of comorbid PTSD greatly interferes with effective SUDs treatment, development of an integrated evidence-based treatment for this population is critical.